From b644ff2d71b07a36609c6a878a6f8e638c74947d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20Bylica?= <pawel.bylica@imapp.pl>
Date: Tue, 7 Oct 2014 16:03:05 +0200
Subject: [PATCH] Stack cleanups

---
 evmcc/Compiler.cpp |  2 +-
 evmcc/Stack.cpp    | 11 +++--------
 evmcc/Stack.h      | 21 +++++++++++++++------
 3 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/evmcc/Compiler.cpp b/evmcc/Compiler.cpp
index 7fccadbf1..1be4a3746 100644
--- a/evmcc/Compiler.cpp
+++ b/evmcc/Compiler.cpp
@@ -186,7 +186,7 @@ std::unique_ptr<llvm::Module> Compiler::compile(const dev::bytes& bytecode)
 	auto ext = Ext(builder, module.get());
 
 	BasicBlock* currentBlock = &basicBlocks.find(0)->second; // Any value, just to create branch for %entry to %Instr.0
-	BBStack stack(builder, extStack); // Stack for current block
+	BBStack stack; // Stack for current block
 
 	for (auto pc = bytecode.cbegin(); pc != bytecode.cend(); ++pc)
 	{
diff --git a/evmcc/Stack.cpp b/evmcc/Stack.cpp
index 1a453d396..1b8577159 100644
--- a/evmcc/Stack.cpp
+++ b/evmcc/Stack.cpp
@@ -21,11 +21,6 @@
 namespace evmcc
 {
 
-BBStack::BBStack(llvm::IRBuilder<>& _builder, Stack& _extStack):
-	m_extStack(_extStack),
-	m_builder(_builder)
-{}
-
 void BBStack::push(llvm::Value* _value)
 {
 	m_block->getState().push_back(_value);
@@ -37,11 +32,11 @@ llvm::Value* BBStack::pop()
 	if (state.empty())
 	{
 		// Create PHI node
-		auto first = m_block->llvm()->getFirstNonPHI();
+		auto i256Ty = llvm::Type::getIntNTy(m_block->llvm()->getContext(), 256);
 		auto llvmBB = m_block->llvm();
 		if (llvmBB->getInstList().empty())
-			return llvm::PHINode::Create(m_builder.getIntNTy(256), 0, {}, m_block->llvm());
-		return llvm::PHINode::Create(m_builder.getIntNTy(256), 0, {}, llvmBB->getFirstNonPHI());
+			return llvm::PHINode::Create(i256Ty, 0, {}, m_block->llvm());
+		return llvm::PHINode::Create(i256Ty, 0, {}, llvmBB->getFirstNonPHI());
 	}
 
 	auto top = state.back();
diff --git a/evmcc/Stack.h b/evmcc/Stack.h
index 06deff814..430389ef9 100644
--- a/evmcc/Stack.h
+++ b/evmcc/Stack.h
@@ -37,22 +37,31 @@ private:
 class BBStack
 {
 public:
-	BBStack(llvm::IRBuilder<>& _builder, Stack& _extStack);
+	BBStack() = default;
+	BBStack(const BBStack&) = delete;
+	void operator=(const BBStack&) = delete;
+
+	/**
+	 Changes current basic block (if any) with a new one with empty state.
+	*/
+	void setBasicBlock(BasicBlock& _newBlock);
 
 	void push(llvm::Value* _value);
 	llvm::Value* pop();
+
+	/**
+	 Duplicates _index'th value on stack.
+	 */
 	void dup(size_t _index);
-	void swap(size_t _index);
 
 	/**
-	 Changes current basic block with a new one with empty state.
+	 Swaps _index'th value on stack with a value on stack top.
+	 @param _index Index of value to be swaped. Cannot be 0.
 	 */
-	void setBasicBlock(BasicBlock& _newBlock);
+	void swap(size_t _index);
 
 private:
-	Stack& m_extStack;                  ///< External (global) stack
 	BasicBlock* m_block = nullptr;		///< Current basic block
-	llvm::IRBuilder<>& m_builder;
 };